A novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019 in China. The mutated coronavirus spread worldwide, and some patients infected with SARS-CoV-2 developed coronavirus disease 2019 (COVID-19) manifested with upper respiratory infection, pneumonia, or respiratory distress. Since the SARS-CoV-2 pandemic was declared with surging confirmed cases and mortality of COVID-19 worldwide, it has reshaped our way of living and how to manage patients with allergic diseases. The medical staff, including allergy specialists, has been at the forefront of fighting against the SARS-CoV-2 pandemic and is struggling to guarantee safety to themselves and their patients. Thanks to vigorous research into the relationship between SARS-CoV-2 and allergic diseases, we have become able to treat allergic patients with the best of evidence to date. The clinician should make a careful decision on each clinical situation with regard to patient characteristics, local and national circumstances as well as the knowledge we have, since it is still limited. We hope further efforts to identify the nature of SARS-CoV-2 and COVID-19 clearer and effective SARS-CoV-2 vaccination will soon remove the grim picture of the worldwide pandemic and bring us back to normal. (Allergy Asthma Respir Dis 2021;9:115-123)

In order to overcome the global pandemic of the new pathogen, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), intensive research has been conducted to understand viral pathogenicity, establish effective treatment strategies, and develop vaccines against coronavirus disease 2019 (COVID-19). To prevent COVID-19, a variety of COVID-19 vaccines have been rapidly developed and are currently being administered worldwide. When developing new vaccines, monitoring for adverse events following immunization (AEFIs) has always been important, and some COVID-19 vaccines are particularly effective as new types of vaccines that have not been used before, thus attracting attention to AEFIs. Vaccine administration is carefully conducted while monitoring for AEFI that are being reported from time to time. AEFIs are largely divided into local reactions, systemic reactions, allergic reactions, and adverse reactions to specific diseases or disease- attributable events. In addition, it is classified according to causes, but it is very difficult to confirm the association with the vaccine. Anaphylaxis, which is a systemic reaction among serious allergic reactions, requires immediate treatment and may require testing to determine the cause. In order to increase the vaccination rate and secure herd immunity, there should be no fear of vaccination due to unidentified side effects. Therefore, monitoring of AEFIs is important and causal relationships must be well established based on reliable epidemiological investigations. Current data show that the benefits of a COVID-19 vaccine far outweigh the risk of AEFIs. Future studies should continue to understand the mechanisms and risk factors of identified adverse reactions. (Allergy Asthma Respir Dis 2021;9:124-135)

Purpose: There are limited data on the epidemiological and clinical characteristics and outcomes in Korean patients with laboratory-confirmed coronavirus disease 2019 (COVID-19). We aimed to describe the epidemiological and clinical characteristics and outcomes of patients with COVID-19 using the Korean nationwide multicenter database.
Methods: In this nationwide multicenter study, we included all confirmed patients of COVID-19 in South Korea from February 1 to April 30, 2020. Subjects were classified into 3 age groups: those at younger than 10 years (children), 10 to 20 years (adolescents), and 20 years or more (adults). Cases were confirmed by laboratory testing using real-time reverse transcriptase-polymerase chain reaction assay and analyzed for epidemiological and clinical features and outcomes. Patents were followed up until April 30, 2020.
Results: Of 5,628 patients with COVID-19 (2,320 males [41.2%] and 3,308 females [58.8%]), there were 66 children (1.2%), 206 adolescents (3.7%), and 5,356 adults (95.2%). The common comorbidities were hypertension (1,201, 21.3%), diabetes (691, 12.3%), dementia (224, 4.0%), chronic heart disease (179, 3.2%), cancer (145, 2.6%), and asthma (128, 2.3%). The common presenting symptoms were cough (2,341, 41.6%), sputum (1,619, 28.8%), fever (1,305, 23.2%), headache (967, 17.2%), myalgia (926, 16.5%), and pharyngodynia (881, 15.7%). One hundred sixty-five patients (2.1%) were confirmed as having moderate or severe COVID-19 and 118 (2.1%) as having severe COVID-19.
Conclusion: Our descriptive study provides the epidemiological and clinical characteristics and outcomes of patients with laboratory-confirmed COVID-19 in South Korea. (Allergy Asthma Respir Dis 2021;9:136-140)

Purpose: Forced expiratory flow between 25% and 75% (FEF25%-75%) is known to sensitively reflect bronchial obstruction. Methacholine challenge test (MCT) has shown varying reduction levels of forced vital capacity (FVC) with the reduction in forced expiratory volume in 1 second (FEV1) in asthma. The aim of this study was to evaluate the clinical implication of provocative concentration causing a 20% fall in FEF25%-75% (PC20-FEF25%-75%) and the percentage fall in FVC at the PC20 dose of methacholine (△FVC).
Methods: A total of 194 children who visited the hospital due to respiratory symptoms and underwent MCT were analyzed retrospectively. The patients were divided into 3 groups. Group I had both PC20-FEV1 and PC20-FEF25%-75% above 16 mg/mL; group II had a PC20-FEF25%-75% that fell below 16 mg/mL but PC20-FEV1 was 16 mg/mL or above; group III had a PC20-FEV1 and a PC20-FEF25%-75% that both fell below 16 mg/mL.
Results: In group II, PC20-FEV1 was lower (P=0.026) and the rate of change in FEV1 and FEF25%-75% from baseline to 16 mg/mL of methacholine concentration was greater than in group I (both P<0.001). Levels of PC20-FEF25%-75% were higher in group II compared to group III (P<0.001). △FVC showed a correlation with PC20-FEV1 (P<0.001) only in the whole group.
Conclusion: In asthmatic children, PC20-FEF25%-75% may be associated with bronchial hyperresponsiveness. △FVC was not associated with other parameters in either group. For subjects with a positive finding of PC20-FEF25%-75% and a negative finding of MCT, the progression to asthma can be suspected. (Allergy Asthma Respir Dis 2021;9:141-147)

Purpose: Inhalant allergens are known as a major factor for respiratory allergic diseases. There are many differences in sensitization rates of inhalant allergens, depending on the environment and demographic factors. This study aimed to compare the cross-sectional differences in sensitivity patterns to inhalant allergen between children, adolescents, and adults.
Methods: We analyzed the results of 449 patients with asthma or allergic rhinitis who underwent the inhalant allergen skin prick test at our university hospital in 2016. The subjects were classified 5 groups according to age: children (≤12 years), adolescents (13-17 years), young adults (18-30 years), middle adults (31-64 years), and elderly group (≥65 years). Positive responses skin prick test for allergens were defined as allergen-to-histamine wheal ratio ≥1.
Results: The sensitization rate (SR) to house dust mites (HDM) was 52.1% on average, showing the highest SR in all groups, especially in children (64.2%). Children and adolescents showed high SRs to cockroach along with tree pollen, animal fur, and adults showed high SR to weed pollen along with them. Among the tree pollen, the SRs to oak, alder, birch, and beech were high in all groups; in children, the SR to plain and willow tended to be high, and in adults the SR to hazel was high. SRs to Timothy pollen (9.9%) and Alternaria (8.6%) tended to be higher in children than in the other groups.
Conclusion: Although HDM is still the major allergen in children and adults with respiratory allergy, our study suggests various differences in the sensitization pattern to inhalant allergens according to age even in the same area. Further studies are needed to explain these differences in sensitization patterns. (Allergy Asthma Respir Dis 2021;9:148-155)

Purpose: Swyer-James-Macleod syndrome (SJMS) is a rare disorder characterized by the hyperlucency of a unilateral lung due to ipsilaterally arrested lung growth. No sufficient information on progressive lung function changes during growth is available in SJMS.
Methods: We retrospectively reviewed SJMS cases using a clinical database from January 2000 to August 2018.
Results: A total of 40 patients were enrolled in this study. The median age of the patients was 4.8 years (interquartile range [IQR], 2.7-9.0 years), boys (n=21, 52.5%) were more affected, and left lungs (n=27, 67.5%) were more involved. The interval between infection and diagnosis was 1.8 years (IQR, 0.7-6.4 years). Mycoplasma pneumoniae (n=14) and adenovirus (n=5) were most prevalent among the 21 subjects with presumably identifiable causes. Most of the 16 patients with available pulmonary function data presented moderate obstructive lung function (z-score, median; FEV1: -4.320 [IQR, -5.955 to -3.400] and FVC: -2.600 [IQR, -3.590 to -1.570], respectively) with the more decreased median in forced expiratory flow between 25% and 75% of FVC (FEF25%-75%) (z-score, -4.470; IQR, -5.330 to -3.170). Linear mixed effect models indicated that younger age at first infectious insult was significantly related to decreased FEV1 z-score (P=0.041), and that the FEV1/FVC and FEF25%-75% z-scores were reduced by 0.082 (P=0.005) and 0.069 (P≤0.001) per year.
Conclusion: In children with SJMS, the initial infectious insult occurs in the early life with M. pneumoniae being the most common pathogen. Lung function may deteriorate with an obstructive pattern during growth. The impairment can progress slowly not in the FEV1, but in the FEV1/FVC or FEF25%-75%. (Allergy Asthma Respir Dis 2021;9:156-163)

Purpose: In 2014, Pusan National University Hospital developed an electronic system for the monitoring and management of adverse drug reactions (ADRs) to iodinated contrast media (ICM) and premedication. We analyzed the prevalence of hypersensitivity reactions (HRs) and the effect of premedication after system development.
Methods: We analyzed immediate HRs to ICM recorded from January 2015 to September 2018 and the annual incidences were compared.
Results: Patients with immediate HRs to ICM were at a mean age of 54.6±14.3 years and 53.8% were female. The overall frequency of HRs was 0.328%. In the classification according to the degree of severity, 87.2% of the cases were mild, 11.0% were moderate, and 1.8% were severe. The ICM most commonly inducing an HR was iomeprol (0.529%), followed by iohexol (0.371%), ioversol (0.359%), iobitridol (0.310%), iopamidol (0.152%), iopromide (0.128%), and iodixanol (0.036%). ICM was readministered to 49.2% of the patients, and immediate HRs recurred in 16.2%. There was no correlation between premedication with an antihistamine and HR recurrence, but premedication with corticosteroids reduced the rate significantly. After development of the electronic monitoring and management system, the HR incidence increased 1.25-fold per year, but most cases were mild and the rate of severe reactions tended to decrease.
Conclusion: Because ADRs to ICM are difficult to predict, appropriate strategies to prevent their development are needed. A system that documents ADRs to ICM can improve patient management. (Allergy Asthma Respir Dis 2021;9:164-170)

Purpose: Many studies have shown that obesity is one of the major causes of lung function decline. However, a longitudinal study of the correlation between changes in obesity degree and lung function is still lacking. This study aimed to analyze alterations in lung function according to changes in body and abdominal fat amount over time in healthy individuals.
Methods: A retrospective cohort study of individuals who received annual health screening was performed. Individuals who underwent health screening at least 3 times with follow-up periods more than 5 years were included. Using a linear mixed model, we analyzed associations between the change in total body fat amount/abdominal fat ratio and lung function decline over time by dividing each quartile according to the fat change rate.
Results: A total of 15,484 individuals over 40 years old was enrolled prospectively. A longitudinal increase in total body fat amount over time was associated with a predicted value of forced expiratory volume in 1 second (FEV1p; %) and predicted value of forced vital capacity (FVCp; %) declines, regardless of sex. A similar phenomenon was observed between an increase in abdominal fat ratio and FEV1p/FVCp decline, which was predominant in males. In addition, the change in abdominal fat ratio showed a significant correlation with differences in the initial values of FEV1p and FVCp after 40 years old.
Conclusion: Increases in total body fat amount and abdominal fat ratio may cause lung function decline over time. (Allergy Asthma Respir Dis 2021;9:171-179)

Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by genetic deficiency or decreased function of C1-esterase inhibitor. It is characterized by swelling of subcutaneous and submucosal tissues of the extremities, gastrointestinal tract, and upper airways which can be life-threatening. Thus, early recognition and treatment of the disease are important. Short- and long-term prophylaxes are used to decrease the severity and frequency of attacks. Icatibant is a selective bradykinin B2-receptor antagonist, earlier treatment of acute attacks and hospital admission. The authors present a case of 47-year-old woman who was diagnosed with type II HAE, danazol as a long term. Her symptoms improved dramatically after drug treatment. The unpredictability and recurrence of HAE attacks could have a negative impact on social life and quality of life. This case shows that timely and proper treatment could improve quality of life and reduce morbidity and mortality. (Allergy Asthma Respir Dis 2021;9:180-183)